Heavily erbium-doped low-hydroxyl fluorotellurite glasses for 2.7 μm laser applications

Heavily erbium-doped low-hydroxyl fluorotellurite glasses with molar compositions of (85.7-x)TeO2 + xBaF(2) + 4.8Na(2)CO(3) + 9.5Er(2)O(3) (x = 38.1, 28.6, 19) were fabricated. The maximum doping concentration of erbium ions was up to 19 mol % by introducing BaF2 into the tellurite glass system. Under 980 nm excitation, intense emissions around 2.7 mu m from the I-4(11/2) -> I-4(13/2) transition of Er3+ ions were observed in these glasses. The efficient mid-infrared emission can be attributed to the existence of cross relaxation (CR) I-4(13/2) -> I-4(15/2) (Er3+): I-4(13/2) -> I-4(9/2) (Er3+) caused by high erbium concentration, low hydroxyl content, and low phonon energy. The stimulated emission cross section at 2.7 mu m of 47.6TeO(2) + 38.1BaF(2) + 4.8Na(2)CO(3) + 9.5Er(2)O(3) glass was calculated as 1.94 x 10(-20) cm(2). Our results indicate that it is a promising gain medium for 2.7 mu m lasers. (C) 2013 Optical Society of America